Known rotators are disclosed in Finnish patent applications 843941 and 823499. It is apparent that the seal between the lamellar vanes and the case in a rotator type machine cannot be effected as well as the seal between a piston and cylinder in a cylinder type machine. In a rotator type machine, a small axial tolerance is provided for the axle to account for heat expansion. This tolerance allows the axle to rotate, even when pressure connections to the rotator are closed. However, it is desirable to lock the axle in place when the rotator is not in use.
In a known rotator, a separate brake device is set around the hydraulic motor. This is a relatively complicated arrangement. In addition, the brake device set around the motor can be easily damaged.